Use `[[maybe_unused]]` in `VariableType_[0-4].cpp` (#100250)
This is kind of trivial, as per title.
Removing `(void)_any_requires_grad` and giving `[[maybe_unused]]` attribute to that variable.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/100250
Approved by: https://github.com/Skylion007, https://github.com/soulitzer
